Approximately 87 percent of the population of the United States will experience some degree of cognitive decline as a consequence of the normal aging process. Normal age-related cognitive decline typically begins at about age 25. Cognitive changes that are typically observed include a reduced numerical/arithmetic ability and the speed at which one processes information. From an individual's late thirties or forties to as late as the individual's 50's or 60's, episodic or declarative memory function typically decreases. Word knowledge, vocabulary, and word reading typically remain stable into late adulthood (age 70 and greater). Typically an individual's attention span decreases with age as well.
Normal age-related cognitive decline is a complex process and is likely related to a deterioration of the various biological systems that underlie cognitive ability (i.e., the ability to think and reason). Age-related insults such as chronic inflammation, oxidative stress, insulin resistance, endothelial dysfunction, and declining hormone levels, are believed to play roles in the physical deterioration of the brain and subsequent age-related decline in cognitive ability. In short, age-related neuroanatomical and biological changes are believed to play a role in the variance in cognitive ability between young and aged individuals.
Normal age-related decline in cognitive ability is implicated in the general decrease in intellectual achievements across a variety of technical fields, including research activities, number of inventions, number of published articles or other creative works such as paintings, and overall production of high-quality products (e.g. highly-cited articles or discoveries recognized as the basis for a Nobel Prize). See e.g. Salthouse, T. 2012. Annu. Rev. Psychol. 63:201-226. The decline in cognitive ability related to the normal aging process has also been implicated in an age-related reduction in job performance. Moreover, the age-related neuro physical deterioration may affect mood, sleep patterns, and overall quality of life.
Given the prevalence and negative consequences of normal age-related cognitive decline, there exists a long-felt need for preventing or delaying the onset of normal age-related cognitive decline and improving the cognitive performance in an individual suffering from normal age-related cognitive decline.